Great apartment! This was my favorite one of all the apartments I stayed in while visiting Bangkok, mostly in the area between BTS Asok and Phloen Chit of Sukhumvit street.
I highly recommend it. It is clean, comfortable, spacious and has a great view.
I will definitely stay again next time I am in Bangkok.
Some points to note:
1. The location is in a very "lively party area", pretty close to to Nana Plaza ("The World's Largest Adult Playground"). This is not a problem as you can walk to the apartment via Soi 6, as explained clearly by the owner, and Soi 4 is just fine during the day. But during the evening/night, men can be approached (even joking aggressively) by working girls, so be aware if you're timid.
2. The building is not new, but the pool is nice, the gym is good, and the apartment itself is lovingly renewed and decorated.
3. The host is very flexible, positive and quickly handled every issue or request I had.
4. There is no smart TV, just Thai cable, so until they add one it might be nice to bring an HDMI cable to connect to your laptop, or a streamer, so you can watch YouTube/Netflix etc.
5. Using GrabBike (or Bolt) is super helpful when staying here.
6. There are three 7/11's minutes away.
7. I highly recommend Tamnanthai (more modern Thai) and Niyom Pochana (local Thai) restaurants that are nearby.